1. Field of the Invention
This invention relates generally to blister sealers and, more specifically, to a Collapsible Rotary Blister Sealer with Improved Heating Plate Assembly.
2. Description of Related Art
Blister packaging has become one of the most prevalent means for packaging small- to medium-sized items for retail sale. A blister package comprises a backing card, many times made from cardboard, with designs or other information labeled thereon; a clear plastic "blister" is then sealed (over the retail item) to the backing card. These blister packages are extremely convenient and cost-effective and are particularly well-suited for hanging from the backing card. These backing cards may also be made from plastic, with a paper or cardboard insert placed in the blister with the retail item.
Prior blister sealers are adequate for the sealing task. They generally comprise at least one nesting tray on which the blisters are staged facing back-side up (i.e. the inside of the blister is up). The retail items are then placed on top of the blister (i.e. inside of it), with the face-down backing card then being laid atop the blister. The nesting tray is then placed under a heated plate; the heated plate is pressed down upon the back of the backing card for the requisite amount of time, which causes the blister to bond to the backing card, usually by melting a special bonding agent previously applied to either the backing card or the blister.
These prior blister sealers are generally very large machines that have more than one work station, typically arranged about a rotatable turntable, such that one set of parts can be staged by one employee coincident with the sealing of another set of parts by another employee. The problem with these large machines is that they are not a feasible purchase for a business having medium- to low-volume packaging needs. For one thing, they are prohibitively expensive; they are also so big that they consume excessive shop space. Furthermore, they are extremely difficult to ship, move or relocate. What is needed is a compact, lightweight blister sealer that can handle low- to medium-work flow. Also, if the unit had detachable legs, such that the unit could not only be easily shipped, but also placed on an existing table-top, the unit would be even more beneficial.
Another difficulty with the prior blister sealers is the design of the turntable. The typical prior turntable is a solid circular board or sheet with apertures cut therein for receiving the nesting trays. When it is necessary to conduct periodic maintenance or repairs, it is extremely difficult to remove these turntables, because of their extreme weight and size, as well as the fact that they are not designed to be easily removed. What is needed is a rotary blister sealer that includes a light-weight, quickly-detachable turntable, to facilitate maintenance on the unit. If the turntable was also collapsible, it would be of farther benefit, particularly if the unit was to be shipped to another location.
Another important part of the blister sealer is the heating plate assembly. The typical prior heating plate assembly comprises a solid metal block, through which passages are drilled. Electric heating coils are then inserted into the passages; when the coils are heated, the block will heat by conduction. One problem with this prior design relates to the need for maintenance on the heater; if a coil fails, many times the entire heating block must be discarded or sent out for repair. If the heating plate assembly included provisions for easy access to the heating coils in the event of coil failure, the user could easily complete repairs without the need to send the heater out for special help.
A further problem with the prior heating plate assembly is that of wear to the face of the heating plate. It is fairly common that the face of the heating plate becomes fouled or otherwise damaged through prolonged use. The prior heating plate assembly must be completely replaced in such an event, creating excessive delays and expense. If there were some sort of shield over the face of the heating plate that could be easily and cheaply replaced when it became worn or damaged, there would be no need to dismantle the entire heating plate assembly for repairs; this would be very helpful.
Another drawback of the prior blister sealers relates to control of the turntable positioning. The typical prior (manual) blister sealer doesn't have any sort of stopping or indexing system for stopping the turntable when a freshly loaded nesting tray is in position for pressing. As a result, misalignments and/or delays may occur while proper positioning is achieved. If the turntable included a series of stops, such that it simply needs to be rotated until a stop is encountered in order to be in correct alignment with the press, it would greatly facilitate the blister sealing process.
The blister sealing process and equipment is closely related to another process, known as "clamshell packaging". The clamshell package is plastic on the front and back side of the packaged item. The conventional manufacturing process creating the clamshell package involves gluing or sealing the edges of the two plastic halves to one another. The conventional clamshell packaging equipment suffers from the same defects as the conventional blister sealing equipment, namely, its extreme bulkiness and high cost. What is needed is a low-cost, collapsible, rotary blister sealer for creating clamshell packages.